.nav_menu{
    position: fixed;
    bottom: 0;
    height: 50px; /*no*/
    background-color: #fff;
    width: 100%;
    display: flex;
    max-width: 480px; /*no*/
    .nav_menu_item{
        flex: 1;
        text-align: center;
        img{
            width: 44px; /*no*/
        }
    }
}